typedef enum  {
    CHANGED,
    UNCHANGED
} t_change;
	
typedef struct {
    char pin_1 : 1;
    char pin_2 : 1;
} t_value;

typedef struct {
     t_change pin_1 : 1;
     t_change pin_2 : 1;
} t_status;

typedef struct {
    t_value value;
    t_status status;
} t_port;


